Facts About Perception

Plato argued that human sight is made possible through a "visual fire" emitted from our eyes and which, when combined with daylight, can detect objects in the world.

If brain space indicates the importance of a sense, then vision is the most important. Roughly 30 percent of neurons in the brain's cortex are devoted to vision, compared with 8 percent for touch, and 2 percent for hearing.

A genetic mutation found in approximately two to three percent of women allows them to see up to 100 million different colors—one hundred times more than the average person.

Scientists have devised a way of reading your mind—or at least determining what you're looking at. By looking at your brainwaves, scientists at Stanford, Ohio State University and the University of Illinois at Urbana-Champaign are able to tell whether you're looking at a photo of a beach, cityscape, forest, highway, mountain or office, just by the pattern in which your neurons fire.

Unlike other senses, human vision is processed in the back of the brain (in a location called the occipital lobe). The senses of smell, taste and hearing are processed in the sides of the brain (in the temporal lobes).

Astronauts have often reported having a diminished sense of taste when in outer space. Scientists believe this has to do with the way that fluids in our bodies react to weightlessness, causing a buildup of fluids in the nasal sinuses.

Based on a study of 190-million-year-old fossils, paleontologist Tim Rowe of the University of Texas has proposed that the reason that mammals (including humans) have larger, more complex brains than other animals is that mammals needed a larger brain to improve their sense of smell—and thus their chances of survival.

While scientists are unsure about how exactly the human nose can detect odors, a recent study suggests that the explanation is based in quantum mechanics—small changes in the energy levels, or quanta, in the electrons of odor molecules.

Between 1 percent and 4 percent of people are believed to have synesthesia, a condition in which sensory input automatically triggers multiple senses. Author Vladimir Nabokov, for example, wrote that he often heard sounds in colors, as did the artist Wassily Kandinsky.

While humans can hear sounds whose frequencies range between 20 Hz and 20,000 Hz, we're most sensitive to frequencies between 2,000 Hz and 4,000 Hz—which happens to be the range of human speech.

Researchers at the University of Pennsylvania have calculated that the human eye can transfer data at the rate of approximately 8.75 megabits per second—roughly triple the speed of the average Internet connection in the United States.

Scientists have found evidence that birds can literally see the earth's magnetic fields.